Vibration actuator, electronic apparatus, and optical apparatus

Abstract

A vibration actuator according to the present invention includes: a vibrator including a piezoelectric material, an electrode disposed on a first surface of the piezoelectric material, and an elastic body disposed on a side of a second surface, opposite to the first surface, of the piezoelectric material; and a contact body that is in contact with the elastic body and is movable relative to the vibrator. The vibrator vibrates when a voltage is applied between the contact body and the electrode with the contact body at a ground potential.

1 . A vibration actuator comprising:
 a vibrator including   a piezoelectric material,   an electrode disposed on a first surface of the piezoelectric material, and   an elastic body disposed on a side of a second surface, opposite to the first surface, of the piezoelectric material; and   a contact body that is in contact with the elastic body and is movable relative to the vibrator,   wherein the vibrator vibrates when a voltage is applied between the contact body and the electrode with the contact body at a ground potential.   
     
     
         2 . The vibration actuator according to  claim 1 , wherein the elastic body and the piezoelectric material are joined via a conductive bonding portion. 
     
     
         3 . The vibration actuator according to  claim 2 , wherein the conductive bonding portion is layered, and an average thickness of the conductive bonding portion is 1.5 μm or greater and 7 μm or less. 
     
     
         4 . The vibration actuator according to  claim 2 , wherein the conductive bonding portion contains conductive particles. 
     
     
         5 . The vibration actuator according to  claim 4 , wherein an average particle diameter of the conductive particles is 1 μm or greater and 5 μm or less. 
     
     
         6 . The vibration actuator according to  claim 4 , wherein the conductive particles are contained in the conductive bonding portion with a volume fraction of 0.4% or greater and 2% or less. 
     
     
         7 . The vibration actuator according to  claim 1 , wherein the contact body includes stainless steel. 
     
     
         8 . The vibration actuator according to  claim 7 , wherein at least one of a surface of the contact body and a surface of the elastic body is covered with a nitride. 
     
     
         9 . The vibration actuator according to  claim 1 , wherein the contact body includes aluminum. 
     
     
         10 . The vibration actuator according to  claim 9 , wherein a surface of the contact body is covered with an oxide of aluminum. 
     
     
         11 . The vibration actuator according to  claim 1 , wherein the elastic body is covered with a conductor. 
     
     
         12 . The vibration actuator according to  claim 1 , wherein the elastic body includes a rectangular portion, and the vibrator is held by a vibrator holding member at four corners of the rectangular portion. 
     
     
         13 . The vibration actuator according to  claim 12 , wherein the elastic body includes a support portion protruding from an end portion of the rectangular portion, and the vibrator is held by the vibrator holding member via the support portion. 
     
     
         14 . The vibration actuator according to  claim 1 , wherein the elastic body has an annular shape. 
     
     
         15 . The vibration actuator according to  claim 1 , wherein the contact body is a stator, and the vibrator is a mover. 
     
     
         16 . The vibration actuator according to  claim 1 , wherein the electrode includes a first electrode and a second electrode that are adjacent to each other. 
     
     
         17 . The vibration actuator according to  claim 12 ,
 wherein, when a first region and a second region are respectively defined as a region in which the first electrode is provided and a region in which the second electrode is provided in the piezoelectric material, the vibrator forms   a first bending vibration mode in which the first region and the second region both extend or contract, and   a second bending vibration mode in which the second region contracts and extends respectively when the first region extends and contracts.   
     
     
         18 . The vibration actuator according to  claim 1 , wherein an electrode of a ground potential is not provided on the first surface of the piezoelectric material. 
     
     
         19 . The vibration actuator according to  claim 1 , wherein a plurality of the vibrators are in contact with the contact body that is common to all of the vibrators, and the contact body and the plurality of vibrators move relative to each other due to vibrations of the plurality of vibrators. 
     
     
         20 . The vibration actuator according to  claim 1 , wherein the piezoelectric material includes a lead zirconate titanate-based material. 
     
     
         21 . The vibration actuator according to  claim 1 , wherein a content of lead in the piezoelectric material is less than 1000 ppm. 
     
     
         22 . The vibration actuator according to  claim 21 , wherein the piezoelectric material includes a barium titanate-based material. 
     
     
         23 . The vibration actuator according to  claim 22 , wherein the piezoelectric material includes a barium calcium titanate zirconate material. 
     
     
         24 . An electronic apparatus comprising:
 a first member;   the vibration actuator according to  claim 1  provided in or on the first member; and   a second member that is connected to the contact body and has a ground potential.   
     
     
         25 . An optical apparatus comprising:
 the vibration actuator according to  claim 1  in a driving unit; and   at least one of an optical element and an imaging element.   
     
     
         26 . A wire-driven actuator comprising:
 an elongated member;   a wire that is inserted through the elongated member and is fixed to a part of the elongated member; and   the vibration actuator according to  claim 1  that drives the wire,   wherein the elongated member bends due to driving of the wire.